This invention relates to plant cryoprotectant compositions and methods for preventing damage to plants caused by exposure to freezing temperatures for limited periods.
Freezing temperatures are a major cause of damage to plants and plant tissue. According to one estimate, approximately $1.5 billion of agricultural products are annually lost to freezing temperatures in the United States. In Florida alone, more than $3 billion of frostdamage to citrus trees has been reported over the last five years.
Numerous methods have been attempted to prevent damage to plants and plant tissue caused by freezing temperatures. One such method involves the development of hardy plant species, a laborious, time consuming and costly proposition. Other methods involve the use of fogs, smoke, protective foams, bags and the like to prevent the escape of heat from the plant. Still other methods involve the use of wind machines, heaters and/or irrigation. However, none of these approaches has proven to be both effective and commercially practical.
A different approach that has been attempted to prevent frost damage to plants involves treatment of the plant with a cryoprotectant composition. During the last 75 years, many compounds have been identified which exert cryoprotection when added to plant tissues. However, in order to be practically useful, such a composition must be non-toxic to plants, environmentally acceptable and relatively inexpensive. The center of research interest in this field has changed from early emphasis on small molecules that penetrate the cell, to more recent exploration of protective effects derived from very large non-penetrating compounds as they affect the properties of the external solution. However, none of these compounds are currently in wide-spread use. A few successful trial cases have been reported, but the chemicals employed have not been generally accepted.